/************************************************************************
                                                                     
   Xceed Ultimate ListBox for Silverlight                                                                                                                                            
   Copyright (C) 2010 Xceed Software Inc.    
                                                                     
   This program is provided to you under the terms of the GNU General Public  
   License version 2 as published by the Free Software Foundation. 
        
   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY, without even the implied warranty of 
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License along 
   with this program, if not, write to the Free Software Foundation, Inc., 
   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

   This program can be provided to you by Xceed Software Inc. under a
   proprietary commercial license agreement for use in non-Open Source
   projects. Visit Xceed.com to find the commercial edition of 
   Xceed Ultimate ListBox for Silverlight.                                    
                                                                      
 **********************************************************************/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;

namespace Xceed.Silverlight.Data
{
  public sealed class IndexBasedDataSourceProvider : ParentDataSourceProvider
  {
    #region Constructor

    public IndexBasedDataSourceProvider( DataSourceProvider dataSourceProvider )
      : base( dataSourceProvider )
    {
      if( dataSourceProvider.GetType() == this.GetType() )
        throw new ArgumentException( "Cannot reference a DataSourceProvider of the same type.", "dataSourceProvider" );

      if( typeof( IndexDataSourceProvider ).IsAssignableFrom( dataSourceProvider.GetType() ) )
        throw new ArgumentException( "The DataSourceProvider must not be of type IndexDataSourceProvider.", "dataSourceProvider" );

      if( !dataSourceProvider.CanCount )
        throw new ArgumentException( "The DataSourceProvider requires count capabilities.", "dataSourceProvider" );

      if( !dataSourceProvider.CanSkip )
        throw new ArgumentException( "The DataSourceProvider requires skip capabilities.", "dataSourceProvider" );
    }

    #endregion

    #region CanCount Property

    public sealed override bool CanCount
    {
      get
      {
        return true;
      }
    }

    #endregion

    #region CanGroupCount Property

    public sealed override bool CanGroupCount
    {
      get
      {
        return false;
      }
    }

    #endregion

    #region CanJumpToItem Property

    public sealed override bool CanJumpToItem
    {
      get
      {
        return true;
      }
    }

    #endregion

    #region CanSkip Property

    public sealed override bool CanSkip
    {
      get
      {
        return true;
      }
    }

    #endregion

    #region CanSort Internal Property

    internal sealed override bool CanSort
    {
      get
      {
        return true;
      }
    }

    #endregion

    #region CanJumpToDeletedItem Internal Property

    internal sealed override bool CanJumpToDeletedItem
    {
      get
      {
        return true;
      }
    }

    #endregion

    #region IsPrimaryKeyVolatile Internal Property

    internal sealed override bool IsPrimaryKeyVolatile
    {
      get
      {
        return true;
      }
    }

    #endregion

    protected override void Initialize()
    {
      m_indexHelper = ( base.CanSort )
                        ? new IndexHelper( this.ChildDataSourceProvider, base.PrimaryKeyInfo )
                        : new IndexHelper( this.ChildDataSourceProvider, Enumerable.Empty<SortDescription>() );

      base.Initialize();
    }

    protected override IEnumerable<SortDescription> GetPrimaryKeyInfo()
    {
      yield return new SortDescription( IndexDataItem.IndexKeyName, ListSortDirection.Ascending );
    }

    internal override IEnumerable<FilterOperator> SupportedFilterOperators( Type dataType )
    {
      if( dataType == typeof( IndexKey ) )
        return Enumerable.Empty<FilterOperator>();

      return base.SupportedFilterOperators( dataType );
    }

    internal override bool IsSortOrderSupported( IEnumerable<SortDescription> sortOrder )
    {
      // We must exclude the index key name from the sorted properties since it is
      // unknown to the underlying DataSourceProvider.
      List<SortDescription> newSortOrder = ( from sd in sortOrder
                                             where sd.PropertyName != IndexDataItem.IndexKeyName
                                             select sd ).ToList();

      if( newSortOrder.Count == 0 )
        return true;

      return base.IsSortOrderSupported( newSortOrder );
    }

    internal sealed override bool CanJumpTo( IEnumerable<SortDescription> properties )
    {
      if( !this.CanJump )
        return false;

      return ( properties != null )
          && ( properties.Any( ( item ) => item.PropertyName == IndexDataItem.IndexKeyName ) );
    }

    internal override bool FindElementMemberType( string memberName, out Type type )
    {
      if( memberName == IndexDataItem.IndexKeyName )
      {
        type = typeof( IndexKey );
        return true;
      }

      return base.FindElementMemberType( memberName, out type );
    }

    internal override IAsyncResult BeginExecuteDataQueryCore(
      DataQueryParameters queryParameters,
      AsyncCallback callback,
      object state )
    {
      return m_indexHelper.BeginGetItems( queryParameters, callback, state );
    }

    internal override DataQueryResult EndExecuteDataQueryCore( IAsyncResult asyncResult )
    {
      DataQueryResult queryResult = m_indexHelper.EndGetItems( asyncResult );

      List<IndexDataItem> dataItems = new List<IndexDataItem>();
      foreach( IndexDataObject item in queryResult.Data.Cast<IndexDataObject>() )
      {
        RawDataItem dataItem = ( RawDataItem )item.DataObject;
        IndexKey key = new IndexKey( this, item.Context, item.Index );
        IndexDataItem newDataItem = new IndexDataItem( dataItem, key );

        dataItems.Add( newDataItem );
      }

      return new DataQueryResult(
               dataItems,
               queryResult.InlineCount,
               queryResult.TotalCount );
    }

    internal override IAsyncResult BeginExecuteStatQueryCore(
      StatQueryParameters queryParameters,
      AsyncCallback callback,
      object state )
    {
      return m_indexHelper.BeginGetStatValue( queryParameters, callback, state );
    }

    internal override StatQueryResult EndExecuteStatQueryCore( IAsyncResult asyncResult )
    {
      return m_indexHelper.EndGetStatValue( asyncResult );
    }

    internal override bool TryWrapDataObject( object item, out RawDataItem dataItem )
    {
      IndexDataItem localDataItem = item as IndexDataItem;
      object childItem = ( localDataItem != null )
                           ? localDataItem.ChildDataItem
                           : item;

      // Make sure the child item is of the appropriate type.
      if( !base.TryWrapDataObject( childItem, out dataItem ) )
        return false;

      if( ( localDataItem == null ) || ( !object.Equals( childItem, dataItem ) ) )
      {
        IndexKey primaryKey = new IndexKey( this, DataQueryContext.None );
        localDataItem = new IndexDataItem( dataItem, primaryKey );
      }

      dataItem = localDataItem;

      return true;
    }

    internal override bool TryUnwrapDataObject( RawDataItem dataItem, out object item )
    {
      IndexDataItem localDataItem = dataItem as IndexDataItem;
      if( localDataItem != null )
        return base.TryUnwrapDataObject( localDataItem.ChildDataItem, out item );

      item = null;
      return false;
    }

    internal override bool TryUnwrapLayer( RawDataItem dataItem, out object item )
    {
      IndexDataItem localDataItem = dataItem as IndexDataItem;
      if( localDataItem != null )
      {
        // Make sure the child data item is of the expected type.
        if( base.TryUnwrapLayer( localDataItem.ChildDataItem, out item ) )
        {
          item = localDataItem;
          return true;
        }
      }

      item = null;
      return false;
    }

    #region Private Fields

    private IndexHelper m_indexHelper;

    #endregion

    #region Private IndexHelper Nested Type

    private class IndexHelper : IndexDataSourceProviderHelper
    {
      internal IndexHelper(
        DataSourceProvider dataSourceProvider,
        IEnumerable<SortDescription> defaultSortOrder )
        : base( defaultSortOrder )
      {
        if( dataSourceProvider == null )
          throw new ArgumentNullException( "dataSourceProvider" );

        m_dataSourceProvider = dataSourceProvider;
      }

      protected override bool CanSortBy( IEnumerable<SortDescription> sortOrder )
      {
        return m_dataSourceProvider.IsSortOrderSupported( sortOrder );
      }

      protected override IAsyncResult BeginCountQuery(
        CountQueryParameters queryParameters,
        AsyncCallback callback,
        object state )
      {
        return m_dataSourceProvider.BeginExecuteCountQueryInternal( queryParameters, callback, state );
      }

      protected override CountQueryResult EndCountQuery( IAsyncResult asyncResult )
      {
        return m_dataSourceProvider.EndExecuteCountQueryInternal( asyncResult );
      }

      protected override IAsyncResult BeginDataQuery(
        DataQueryParameters queryParameters,
        AsyncCallback callback,
        object state )
      {
        return m_dataSourceProvider.BeginExecuteDataQueryInternal( queryParameters, callback, state );
      }

      protected override DataQueryResult EndDataQuery( IAsyncResult asyncResult )
      {
        return m_dataSourceProvider.EndExecuteDataQueryInternal( asyncResult );
      }

      protected override IAsyncResult BeginGroupCountQuery( 
        GroupCountQueryParameters queryParameters, 
        AsyncCallback callback, 
        object state )
      {
        throw new NotSupportedException();
      }

      protected override GroupCountQueryResult EndGroupCountQuery( IAsyncResult asyncResult )
      {
        throw new NotSupportedException();
      }

      protected override IAsyncResult BeginStatQuery(
        StatQueryParameters queryParameters,
        AsyncCallback callback,
        object state )
      {
        return m_dataSourceProvider.BeginExecuteStatQueryInternal( queryParameters, callback, state );
      }

      protected override StatQueryResult EndStatQuery( IAsyncResult asyncResult )
      {
        return m_dataSourceProvider.EndExecuteStatQueryInternal( asyncResult );
      }

      private DataSourceProvider m_dataSourceProvider;
    }

    #endregion
  }
}
